1. Field of the Invention
The present invention relates to signature handling equipment which supplies signatures in an on-edge orientation one at a time to bindery equipment. The invention particularly cooperates with a hopper loader apparatus which transfers and separates individual signatures of sheet materials from a vertically aligned, stack of such signatures. The separated, individual signatures may then be subjected to bindery operations such as stapling or stitching.
2. Description of the Related Art
It is usual in the graphic arts that sheet materials such as newspapers, books, printed cartons and the like emerge from a printing operation in a serial stream of partially overlapping signatures in shingled form. Such a stream of signatures is collected on a conveyor and moved to a stacker for aligning. The stacker receives the sheets in a serial mode from the conveyor and forms an aligned stack for removal and transportation. While large numbers of signatures can be conveniently handled in stack form, some operations on the signatures can only be performed individually. These include such bindery operations as stitching and stapling, among others. It therefore becomes necessary to separate individual signatures from a stack for individual treatment. A signature feed assembly is commonly used to feed signatures one at a time from a hopper onto a conveyor. One known assembly for feeding signatures one at a time onto a conveyor is disclosed in U.S. Pat. No. 4,180,255. Known signature supply assemblies have previously been used to supply signatures to a hopper in a signature feed assembly. Known signature supply assemblies or hopper loaders are disclosed in U.S. Pat. Nos. 3,674,258 and 3,945,633. The signature supply assemblies disclosed in the aforementioned patents supply signatures to a hopper in a generally horizontal orientation. Although hopper loaders are known in the art to supply a stream of generally horizontally positioned signatures, upstanding on-edge vertical signatures are generally required for feeding the signatures one at a time for processing by many stitcher lines.
Signature supply assemblies for supplying signatures in a vertical, an on-edge orientation are disclosed in U.S. Pat. Nos. 4,177,982 and 4,436,297. The complicated nature of the construction and mode of operation of known on-edge signature supply assemblies increases the probability of a jam or other malfunction during operation of the signature supply assemblies. In addition, the more complicated the construction of the signature supply assembly, the greater will be the cost of construction. The present invention seeks to simplify hopper loader construction cost.
It has been a problem in the art to reliably provide an efficient and effective means of separating a stack into its individual signatures for presentation to such bindery equipment. Prior art hopper loaders do not run reliably with a large range of signature sizes. The paper stock may range from heavyweight to lightweight and from a few pages per signature to many pages per signature. This difference in paper weight and/or pagination has required the operator to perform many adjustments to make the machine ready for a production run.
In addition, prior art hopper loaders for bindery equipment must be relatively fixed in position. That is, due to its complexity and the need to critically place the hopper loader in correct position adjacent to the bindery equipment, the hopper loader has not been mobile. That is, one cannot easily move the prior hopper loaders from one piece of bindery equipment to another. The present invention seeks to enhance hopper loader mobility. In the past, a stacked pile of printed signatures has been moved on a horizontal conveyor to an upwardly moving conveyor where both conveyors travel at the same speed. Such an operation has many disadvantages since the stack does not reliably separate into evenly spaced overlapping individual signatures. This unevenness inevitably leads to down stream signature jams and misfeeds requiring considerable operator attention. U.S. Pat. No. 4,180,259 discloses a system for varying the drop of sheets into a hopper. Signatures are fed in a shingled stream and dropped one-by-one into a hopper, which then feeds a gathering chain. Signatures are stripped from a stack and are passed around a complex series of rollers and a large drum ultimately to a pocket. U.S. Pat. No. 5,374,050 discloses a conveyor wherein a stream of signatures is moved upwardly to a pocket having a jogger for the stacked stream of signatures. Difficulties in operating vertical loaders such as disclosed in these prior patents arise in that a large quantity of signatures cannot be loaded in the loader without interfering with the feeding of signature at the supply station, and the loaders cannot handle very short and very long signatures without substantial changes in the feeding mechanism. Further, the signatures are subjected to a constant riffling, sliding and jostling action that results in damage to the folds on the signatures when they move between conveyor belts. U.S. Pat. No. 4,973,038 also discloses a signature handling apparatus, however, this disclosure uses a horizontal feed conveyor which requires a stack pusher. The signatures tend to slide down a second ramp conveyor and hence require a retainer wedge. The present invention operates in the absence of such a pusher.
The present invention provides a vertical loader which avoids or reduces problems encountered in the prior art. The present invention pertains to an apparatus for separating individual signatures which are substantially vertically aligned on a folded edge from a stack of signatures and then feeding them into a pocket from which they are fed by a feed mechanism to bindery equipment. Individual signatures flow reliably, one-by-one out of the pocket to bindery equipment. The simplified equipment is economical, mobile, and signature size changeovers are easy to accomplish.
These and other features, advantages and improvements will be in part discussed and in part apparent to one skilled in the art upon a consideration of the detailed description of the preferred embodiment and the accompanying drawings.